E. coli 0157:H7 is a foodborne pathogen which possesses several virulence factors including the production of toxins. The toxins are members of the Shiga toxin family and therefore are called Shiga-like toxins (SLTs). Two hypothesizes could explain the release of the toxins, release through transport system in the outer membrane or through phage induced lysis. Other EM preparative techniques have inadequately preserved E. coli to pamit studies of the membrane system. Therefore we intend to use high pressure freezing preparative techniques to presave the periplasmic space intact in the E. coli. Using gold labeled antibodies and TEM it should be possible to see a toxin release system through the outer membrane. The absence of a transport system and the presence of complete phages would indicate a phage release system.